施工期混凝土材料特性对其后期耐久性能影响研究

发布时间：2018-02-01 04:41

本文关键词： 混凝土施工期全寿命早龄期材料性能耐久性控制技术　出处：《浙江大学》2013年硕士论文　论文类型：学位论文

【摘要】：由于世界范围内工程结构耐久性问题的逐渐突出,混凝土材料与结构的耐久性问题及其全寿命性能研究已经成为国际研究的热点问题。但是,目前国内外的研究受学科所限,或注重了材料层次的耐久性,或注重了完好结构的性能退化,忽略了结构建造时期材料与结构性状对后期耐久性能的影响。由于混凝土耐久性研究与混凝土早期状态有着密不可分的关系,从混凝土生命周期的源头出发,研究施工期混凝土早龄期材料性能对其后期耐久性能影响的规律,对于混凝土全寿命性能研究具有重要意义。本文从混凝土施工期出发,以研究施工与养护环节中混凝土早龄期性能对服役条件下混凝土耐久性能的影响为出发点,通过试验研究为手段,系统的研究了四种不同振捣及养护工况下混凝土早龄期材料性能对后期耐久性能的影响规律。本文的研究成果对于建立基于早龄期性能分析的混凝土材料耐久性控制技术具有重要的应用价值。本文的主要研究内容如下： (1)对四种不同振捣、养护工况下的混凝土试件进行试验,研究不同施工条件下混凝土28d龄期内的材料性能,包括混凝土的坍落度、水化热和含气量、收缩性能、强度指标、弹性模量和均匀密实性。揭示了施工期振捣、养护条件对混凝土早期性能的影响规律,以及混凝土早期性能时变规律。提出,为了使混凝土早期性能符合标准,施工期必须充分振捣并注意加强7d内的养护措施。 (2)对四种不同振捣、养护工况下的混凝土试件进行试验,研究不同施工条件下混凝土后期各项耐久性指标的随时变化规律,包括透气性指标、氯离子侵蚀浓度、钢筋腐蚀电流密度。揭示了施工期振捣、养护条件对混凝土后期耐久性能的影响规律,研究了基于早龄期性能分析的混凝土材料耐久性控制技术。提出,混凝土结构质量验收过程中,仅以混凝土强度作为验收标准是不合理的,有必要引入渗透性的指标如透气指标等参数以保证混凝土服役期的耐久性能符合标准。 (3)基于扫描电子显微镜的背散射成像技术和压汞法,对不同振捣、养护条件下四组混凝土试件进行了微观孔隙率和孔结构测试,研究了施工工况对混凝土微观结构的影响,并揭示了施工工况对混凝土性能产生影响的微观机理。
[Abstract]:Due to the worldwide durability of engineering structures, the durability of concrete materials and structures and their lifetime performance research has become a hot issue in international research. At present, the research at home and abroad is limited by the discipline, either pay attention to the durability of the material level, or pay attention to the performance degradation of the intact structure. The influence of materials and structural properties on the later durability is neglected. Because the durability of concrete is closely related to the early state of concrete, the source of the life cycle of concrete is considered. It is of great significance to study the effect of early age material performance on the later durability of concrete during the construction period. In this paper, starting from the concrete construction period, in order to study the effect of the early age performance of concrete on the durability of concrete in the construction and maintenance links, through the means of experimental research. The effects of early age material properties on later durability of concrete under four different vibration and curing conditions were systematically studied. The results of this paper are useful for the establishment of durability of concrete materials based on early age performance analysis. Control technology has important application value. The main contents of this paper are as follows:. 1) four kinds of concrete specimens under different vibration and curing conditions were tested to study the material properties of concrete in 28d age under different construction conditions, including slump, heat of hydration and gas content of concrete. Shrinkage property, strength index, elastic modulus and uniform compactness. The effect of vibration and curing conditions on early performance of concrete and the time-varying rule of early performance of concrete are revealed. In order to make the early performance of concrete conform to the standard, it is necessary to vibrate fully during the construction period and pay attention to strengthening the maintenance measures within 7 days. (2) four kinds of concrete specimens under different vibration and curing conditions were tested to study the variation law of concrete durability indexes at different construction conditions, including permeability index. Chloride ion corrosion concentration and corrosion current density of steel bars reveal the influence of vibration and curing conditions on the later durability of concrete. The durability control technology of concrete materials based on early age performance analysis is studied. It is proposed that it is unreasonable to take concrete strength as the acceptance criterion in the process of quality acceptance of concrete structures. It is necessary to introduce permeability index such as permeability index to ensure the durability of concrete service life can meet the standard. Based on the backscattering imaging technique of scanning electron microscope and mercury injection method, the microcosmic porosity and pore structure of four groups of concrete specimens under different vibrational and curing conditions were tested. The influence of construction conditions on the microstructure of concrete is studied, and the microscopic mechanism of the influence of construction conditions on the performance of concrete is revealed.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528

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